1. Field of the Invention
The present invention relates to an inspection apparatus and an inspection method for inspecting a subject using a terahertz wave. In the present specification, an electromagnetic wave having a frequency range including at least a portion of a range from 30 GHz to 30 THz, inclusive, is referred to as a terahertz wave.
2. Description of the Related Art
Conventionally, Fourier analysis has been used to study the frequency dependence of an absorption rate and a refractive index of a sample (subject) from a time waveform of a terahertz wave transmitted through or reflected off of the sample.
However, in a wide frequency range included in the time waveform of a terahertz wave, the frequency dependence of an absorption rate and a refractive index is unique to each material. In this case, an increase in the amount of data to be compared becomes problematic.
In order to solve the problem described above, Japanese Patent Application Laid-Open No. H10-153547 discloses a method for compressing dispersion-related information included in a time waveform of a terahertz wave into a small amount of data and identifying components of a material from the compressed data. Japanese Patent Application Laid-Open No. H10-153547 discloses the use of wavelet analysis as a compression method thereof.